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Around 1960 my family (parents, 5 kids and their friends) spent 3 summers building a 2 story 30×30 summer cottage out of concrete blocks with poured concrete floors and roof on steel pans and joists. The concrete was mixed in a small electric mixer and poured in 5 x 30 strips with cold joints. The windows had single extrusion industrial aluminum frames. The outside was whitewashed and the inside was painted for the most part with water based paint. The location is in Ontario Canada just north of the 45th parallel.
The building always had severe moisture leakage and condensation problems and was impossible to heat. My wife and I are hoping to retire there. We recently put on a conventional wood truss and steel sheet roof and insulated on top of the old concrete roof with 14” to 16” of cellulose. We replaced the windows with vinyl, (low E, argon filled glass) and had 3 inches of Dow blue extruded interior styrofoam (R15) fastened to the outside with strapping and Tapcon screws. This was covered with vinyl siding. This has made the building liveable in summer using dehumidifiers and heatable in winter using high efficiency wood fireplace inserts. The concrete provides a wonderful heat sink in the winter so that once the building is warmed up it doesn’t matter if the fire goes out for awhile at 0 F. or less.
What I need is advice on vapor barriers and inside insulation. For this latitude R27 is recommended for the walls. I would like to lose as little inside space as possible. How much insulation should I put on the inside? What material? Should the vapor barrier go on the concrete block wall or between the insulation and the drywall? Do the steel pans under the ceilings constitute vapor barriers? I have heard that only 1/3 of the total R-value should be on the inside of concrete block walls. Can insulation be installed under the ceiling of the first floor i.e. under the steel pan of the 2nd floor? What about a vapor barrier in this case? Are there any readings available on this subject?
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Ted...again.. if you already have 14-16 inches of cellulose above the old concrete ceiling /roof..why wud u put insulation below the ceiling..
can't u increase the amount of insulation above the ceiling to say 18 - 20inches of cellulose?
and what are the ceiling heights?
it seems to me that u want to measure the humidity in the dwelling.. if it is elevated then i wud guess your source is the concrete floor... consider breaking up the floor ,excavating and compacting with new gravel, putting two or three inches of foam down and pouring a new floor,
or even installing a radiant floor system...
the windows sound good, the exterior insulation sounds weak on the walls , but don't know if i would add anything to the interior...
can u do a heat loss and analyize the different sections to determine your best improvemnet areas?
don't forget, the floor is a constant drain of heat too, and it is also PROBABLY the source of the moisture for your condensation problems...
cure= raise the temperature of the surface above the dew point.... or reduce the moisture in the air..
but for good health the R.H. should be in the 40 to 60 % range...
Mike
*You have a good setup to use the thermal mass of the concrete for heating efficiency. Since you already have insulation on the outside of the walls, why not simply add another R-15 there? Then install radiant floor heat or better yet if you want to heat with wood a masonry heater (you can get a nice once from Heat-Kit right there in Ontario.) While redoing the exterior insulation you should also excavate around the foundation and put in excellent drainage as well as some wing insulation- look for info on frost-protected shallow foundations and try to retrofit to those specs. Depending on your ceiling hieght in the first floor and your solar exposure you might also want to take a look at James Kachadorians solar slab design; if you had the room to retrofit that you could add an additional vapor barrier over the existing slab to help with the moisture. In any case you should look at all that concrete as an investment in thermal mass which can save you lots of heating dollars in the future.
*Thanks Mike and Hot. The foundation is on solid granite rock and there is a sealed basement/crawl space varying from 0 to 8 feet from the bare rock floor (no leaks in this floor). The concrete floors and roof are 2" thick with 1/4" rebar on a 1 ft. grid. While insulating above grade on the exterior, we excavated around the foundation, pressure washed and sealed it with a bituminous coating, glued on 4" of SM, and put in French drains. Depth of foundation below grade varies from 0 to 6 ft. Moisture leaks are no longer a problem in the roof or the basement walls. Ceiling heights are 8 ft. on each floor. There are doors at the top of each staircase so that we can heat each floor independently. The high efficiency wood fireplace inserts work great on both floors. My main concern is with vapor barriers (there are none at present) and upgrading the insulation while finishing the interior walls.
*How much wood do you use in a winter season? I would strongly recommend looking at a thermal mass type heater. If this interests you you should contact Norbert Senf who makes the HeatKit- he is very knowledgable about heating this way. He also lives in Ontario so would be able to address your climate directly. You could get down to 1 or 2 cords a winter I would bet.The disadvantage to insulating on the inside is that you then lose the advantage of that thermal mass in the walls.Best of luck; sounds like a nice spot up there. Cottage country?
*If you're storing firewood inside the thermal boundary, that's probably a major contributor to the moisture problems such as are leading to condensation on the windows.
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Around 1960 my family (parents, 5 kids and their friends) spent 3 summers building a 2 story 30x30 summer cottage out of concrete blocks with poured concrete floors and roof on steel pans and joists. The concrete was mixed in a small electric mixer and poured in 5 x 30 strips with cold joints. The windows had single extrusion industrial aluminum frames. The outside was whitewashed and the inside was painted for the most part with water based paint. The location is in Ontario Canada just north of the 45th parallel.
The building always had severe moisture leakage and condensation problems and was impossible to heat. My wife and I are hoping to retire there. We recently put on a conventional wood truss and steel sheet roof and insulated on top of the old concrete roof with 14” to 16” of cellulose. We replaced the windows with vinyl, (low E, argon filled glass) and had 3 inches of Dow blue extruded interior styrofoam (R15) fastened to the outside with strapping and Tapcon screws. This was covered with vinyl siding. This has made the building liveable in summer using dehumidifiers and heatable in winter using high efficiency wood fireplace inserts. The concrete provides a wonderful heat sink in the winter so that once the building is warmed up it doesn’t matter if the fire goes out for awhile at 0 F. or less.
What I need is advice on vapor barriers and inside insulation. For this latitude R27 is recommended for the walls. I would like to lose as little inside space as possible. How much insulation should I put on the inside? What material? Should the vapor barrier go on the concrete block wall or between the insulation and the drywall? Do the steel pans under the ceilings constitute vapor barriers? I have heard that only 1/3 of the total R-value should be on the inside of concrete block walls. Can insulation be installed under the ceiling of the first floor i.e. under the steel pan of the 2nd floor? What about a vapor barrier in this case? Are there any readings available on this subject?